A vehicle frequently includes displaceable panels such as doors, hood, trunk lid, hatch and the like which are affixed for hinged or sliding engagement with a host vehicle body. Cooperating systems of latches and strikers are typically provided to ensure that such panels remain secured in their fully closed position when the panel is closed.
A door latch typically includes a fork bolt that is pivoted between an unlatched position and a primary latched position when the door is closed to latch the door in the closed position. The fork bolt is typically held in the primary latched position by a detent lever that pivots between an engaged position and a disengaged position. The detent lever is spring biased into the engaged position and thus, holds the fork bolt in the primary latched position when in the engaged position and releases the fork bolt when it is moved to the disengaged position so that the door can be opened.
The fork bolt is pivoted to the primary latched position by a striker attached to, for example, an associated door jamb when the door is closed. Once in the primary latched position, the detent lever engages the fork bolt to ensure the assembly remains latched.
Some vehicles have power unlatching mechanisms that electrically release the door latch. These power unlatching mechanisms moves the detent lever from the engaged position to the disengaged position such that the fork bolt can be rotated or pivoted to the unlatched position. However and when an external condition or force is applied to the door the door may not “pop open” freely and if the power unlatching mechanism is subsequently disengaged the detent lever returns to the engaged position by the spring biasing force and the door cannot be opened even though an electric release command was provided.
Latches mounted in the rear of the vehicle that need to be FMVSS compliant with Federal Motor Vehicle Safety Standards (FMVSS) usually use one switch that signals when the fork bolt is in a position other than the primary latched position. This type of latch typically uses a hold open or snow lever that keeps the detent in the released position when the latch is power released but there is an external load keeping the door closed. This condition can cause a latch to be in a primary position but the detent lever would be in the released position. Hence the door would be closed but the latch would not be latched.
In order to avoid the above described condition some latch manufactures add a switch on the detent that signals when the detent lever is in the released position. If only this detent switch is added and not the fork bolt switch then there is no way of knowing if the latch is in primary, secondary or open when the detent is being held open. Thus, typically two separate switches are employed to determine the state of the fork bolt and the detent lever.
Accordingly, it is desirable to provide an automatically operated door latch assembly. More specifically, it is desirable to provide an automatically operated door latch assembly that is able to provide the status of the fork bolt and the detent lever with a minimal amount of components.